Unimolecular decomposition of methyl chloride. II. Some refinements of the calculations

The quantum version of the statistical collision theory is applied to the unimolecular decomposition of methyl chloride in the second-order region using an improved computational procedure and a more realistic physical model. An attempt is made to determine active degrees of freedom, i.e. degrees of freedom participating in intramolecular energy transfer, by rational argument. These considerations point to at least one overall rotation as active, in addition to all nine vibrations as active. Conservation of angular momentum is explicitly considered in the case of one active rotation and an appropriate correction factor is included in the calculated rate constant, as is a correction for anharmonicity. The theoretical rate constant so computed is within less than a factor of two of the experimental value.